Conventionally, in electromagnetic switching devices, some of them have been used for the purpose of making and breaking an electric power circuit of a vehicle, using the format whereby the contact mechanism is operated by opening and closing with an electromagnetic actuator. As examples of these types of electromagnetic switching devices, the ones shown in FIGS. 19, 20 and 21 are well known. These types of examples include the Japanese Patent Laid-Open Publication No. 2002-42628.
This electromagnetic switching device consists of a body 11 made of resin (plastic), an electromagnetic actuator 2, a pair of fixed terminals 3, a movable contact 4, a shaft 5, etc. as shown in the Figure.
The body 11 is formed into a box shape that is cut in half, and the main body of the electromagnetic switching device is placed inside. The body 11 has mountings 13 on the right and left sides (the same as the right and left sides in the Figure) to fix the electromagnetic switching device to the external attaching part. Also, the body 11 has a lead-out groove (not shown in the Figure) to expose the terminal area 31 of the fixed terminals 3 from the inside to the outside in order to connect it to an external circuit.
The electromagnetic actuator 2 consists of a solenoid coil, top and bottom yokes (the same top and bottom as in the Figure), a movable iron core, etc. The solenoid coil 21 consists of a cylindrical bobbin 21a, which has flanges on the top and bottom, with the conducting wire wound around it, and both ends of the conducting wire are led to the outside of the body 11 (not shown in the Figure). A first yoke 23 is placed from the middle of the inner circumference surface to the upper surface of the solenoid coil 21, and a second yoke 24 is placed from the lower part of the inner circumference surface to the bottom surface and the outer circumference surface of the solenoid coil 21, and these, the first yoke 23 and the second yoke 24, form the magnetic gap with the magnetic poles facing each other inside the solenoid coil as well as the magnetic path.
A movable iron core 22 has a part of itself intervening in the magnetic gap mentioned above, and has the rest of itself in the internal cylindrical part of the second yoke 24. Also, the movable iron core 22 is biased to the direction such that the magnetic gap can be made larger (to the bottom of the Figure) by a coil spring 22a. Therefore, when the solenoid coil 21 is excited, the movable iron core 22 moves up in order to lessen the magnetic gap, and when the excitation is stopped, it moves down by the coil spring 22a. 
The fixed terminal 3 is built with the rectangular shaped conductive plate bent twice in a same direction and both ends turned in a same direction. The fixed terminal 3 has the terminal area 31 outside of the body 11 and has a fixed contact point 32 facing downward inside the body 11 as well.
The movable contact 4 is built to have movable contact points 41 each respectively facing opposite to said fixed contact points 32 on both ends of the rectangular shaped long conductive plate with the center part bent downward, and it is fixed under a retentive part 51 that is formed on the upper part of the shaft 5. The movable contact 4 is pushed up against the headliner of the retentive part 51 by contact pressure springs 41a under the retentive part 51.
The shaft 5 has the bottom end of the connecting axis that extends downward from said retentive part 51 and is fixed into the movable iron core 22, and is placed on the central axis of the electromagnetic actuator 2. The shaft 5 is movable up and down within a specified range inside the electromagnetic actuator 2. The lowest limit of the movement is the point where the bump of the diameter expansion part of the shaft 5 contacts with the insertion hole on the central axis of the first yoke 23, and the cushioning component 53a is placed on the contact point. Additionally, the upper limit of the movement is the point where the upper end of the movable iron core 22 contacts with the lower end of the first yoke 23.
On the lateral side that is outside the body 11 and that the fixed contact points 32 and the movable contact points 41 contact and detach, a yoke 64 that forms the magnetic path and a pair of permanent magnets 65 for generating the magnetic field are placed. The permanent magnets 65 are placed with the magnetic poles facing each other in order to quickly extinguish an arc, which is generated when the fixed contact points 32 and the movable contact points 41 contact and detach, by the magnetic field of the permanent magnets.
When the electromagnetic switching device with the mechanism described above is brought into action and the movable iron core 22 is moved up and down by the electromagnetic actuator 2, the pair of movable contact points 41 of the movable contact 4 each respectively contact with and detach from the pair of fixed contact points 32 through the shaft 5 that moves up and down. Because of this, the circuit between the terminal areas 31 on the pair of fixed terminals 3 is electrically opened and closed through the movable contact 4.
However, because the existing electromagnetic switching devices mentioned above have space (extinguishing space SP) to scatter the energy of the arc by stretching the arc spatially for the purpose of quickly extinguishing the arc generated at the time of opening and closing of the circuit, there is a problem that it is difficult to miniaturize the electromagnetic switching devices. Because the space around the solenoid coil 21 is to be used as the space for extinguishing the arc, there is a possibility of the arc approaching the winding wire of the solenoid coil 21, and it is preferable to avoid this type of mechanism in order to maintain the insulation performance between the circuit side opened and closed (the primary side) and the controlling side of the electromagnetic switching device (the secondary side).
In addition, the arc is occasionally brought into contact with the resin of the body 11 to generate an extinguishing gas, and in this case, because it is necessary to enclose the extinguishing space with the resinous component that generates the extinguishing gas, there is a limit in miniaturizing the electromagnetic switching device. Also, when the electromagnetic switching device is used for electric vehicles, it is preferred to decrease further the operating noise of the electromagnetic switching device, etc. in order to keep the environment inside the vehicles preferable. This is because the motor that directly generates turning force is used as the drive source and the drive source is quiet unlike the existing petrol engine, etc. that uses explosive burnings as the drive force.
This invention aims at providing an electromagnetic switching device that can be miniaturized, can be made at low cost and is quiet, as well as being able to extinguish the arc quickly.